In this paper, a novel fixed-time second-order sliding mode (SOSM) controller has been developed for a class of nonlinear systems with output constraints. Based on the output constraint condition, a new barrier Lyapunov function, which can be used to deal with the output constraint, is first constructed. Then, with the help of adding a power integrator technique, the SOSM algorithm can be constructed step by step. The feature of the proposed SOSM algorithm lies in that it will not only fixed-time stabilize the sliding variable to the origin, but also keep the output variable staying inside the constraint set. This also implies that the setting time of sliding variables will be independent of their initial conditions. Finally, the feasibility and effectiveness of proposed SOSM control method are verified by a numerical example and a practical pendulum system.

在本文中，针对一类具有输出约束的非线性系统，开发了一种新颖的固定时间二阶滑模（SOSM）控制器。根据输出约束条件，首先构造一个新的屏障李雅普诺夫函数，该函数可用于处理输出约束。然后，借助于添加功率积分器技术，可以逐步构建SOSM算法。提出的SOSM算法的特点在于，它不仅可以将滑动变量固定时间稳定到原点，而且可以使输出变量保持在约束集中。这也意味着滑动变量的设置时间将与其初始条件无关。最后，